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Light control film

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20120314276 patent thumbnailZoom

Light control film


Disclosed is a light control film comprising: two of transparent conductive resin substrates each having a transparent conductive layer and a transparent resin substrate; and a light control layer interposed between the two transparent conductive resin substrates to be in contact with the transparent conductive layer sides, the light control layer containing: a resin matrix; and a light control suspension dispersed in the resin matrix, wherein the transparent conductive layer contains: an organic binder resin; and a conductive polymer. The present invention can provide a light control film having satisfactory adhesiveness between the light control layer and the transparent conductive layer and having excellent radio wave transparency.
Related Terms: Light Control Film

Inventors: Satoyuki Nomura, Yoshii Morishita, Tooru Tanaka
USPTO Applicaton #: #20120314276 - Class: 359296 (USPTO) - 12/13/12 - Class 359 


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The Patent Description & Claims data below is from USPTO Patent Application 20120314276, Light control film.

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TECHNICAL FIELD

The present invention relates to a light control film having a light control function.

BACKGROUND ART

A light control glass containing a light control suspension was first invented by Edwin Land, and the light control glass is in the form of a structure in which a liquid-state light control suspension is inserted between two of transparent conductive substrates having a narrow gap therebetween (see, for example, Patent Documents 1 and 2). According to the invention by Edwin land, the liquid-state light control suspension inserted between the two transparent conductive substrates is such that when an electric field is not applied, as a result of the Brownian motion of light control particles that are dispersed in the suspension, most of the incident light rays are reflected, scattered or absorbed by the light control particles, and only a very small portion is transmitted.

That is, the extent of transmission, reflection, scattering or absorption can be determined on the basis of the shape, nature and concentration of the light control particles dispersed in the light control suspension, and the amount of light energy irradiated. When an electric field is applied to a light control window which uses a light control glass having the above-described structure, an electric field is formed in the light control suspension through the transparent conductive substrates, and the light control particles that exhibit a light control function cause polarization and are arranged in parallel to the electric field. Then, light is transmitted between light control particles, and eventually, the light control glass becomes transparent. However, such an initial light control apparatus had problems in practical use, such as the aggregation of the light control particles inside the light control suspension, sedimentation due to their own weights, color phase change due to heat, changes in the optical density, deterioration caused by ultraviolet ray irradiation, difficulties in keeping up the gap between the substrates and in the injection of the light control suspension into the gap, and others. Accordingly, it was difficult to put the light control apparatus to practical use.

Robert L. Saxe, F. C. Lowell, and R. I. Thompson have respectively disclosed light control windows making use of light control glasses for which the initial problems of light control windows, namely, the aggregation and sedimentation of light control particles, changes in the optical density, and the like have been compensated (see, for example, Patent Documents 3 to 9). In these patented inventions, those initial problems are solved by using a liquid-state light control suspension, which includes needle-shaped light control crystal particles, a suspending agent for dispersing crystal particles, a dispersion control agent, a stabilizer and the like, and preventing the sedimentation of light control particles by matching the densities of the light control particles and the suspending agent to be almost equal, while preventing the aggregation of the light control particles by adding a dispersion control agent to increase the dispersibility of the light control particles.

However, since even these light control glasses also have a structure in which a liquid light control suspension is encapsulated in a gap between two transparent conductive substrates as in the case of conventional light control glasses, there is a problem that, in the case of the manufacture of large-sized products, uniform encapsulation of the suspension in the gap between the two transparent conductive substrates is difficult, and a swelling phenomenon in the lower part is likely to occur due to the difference in the hydraulic pressure between the upper part and the lower part of the product. Furthermore, when the gap between the substrates is changed due to the external environment, for example, the pressure of wind, the optical density is changed as a result, so that the color phase becomes inhomogeneous, Further, there is a problem that the sealing material in the peripheral area for holding a liquid between the transparent conductive substrates is destroyed, and the light control material leaks out. In addition, unevenness occurs in the response time as a result of deterioration by ultraviolet ray, and a decrease in the voltage between the peripheral areas and the center of the transparent conductive substrates.

As a method of improving this, there has been suggested a method of mixing a liquid light control suspension with a solution of a curable polymer resin, and producing a film by using a phase separation method based on polymerization, a phase separation method based on solvent volatilization, a phase separation method based on temperature, or the like (see, for example, Patent Document 10).

Furthermore, in a space surrounded by the light control glasses used heretofore, since the transparent conductive resin substrates used in the glasses have small surface resistivity and low radio wave transparency, there is a problem that television sets, mobile telephones, remote control devices utilizing radio waves, and the like may not function adequately.

CITATION LIST Patent Literatures

Patent Literature 1: U.S. Pat. No. 1,955,923 Patent Literature 2: U.S. Pat. No. 1,963,496 Patent Literature 3: U.S. Pat. No. 3,756,700 Patent Literature 4: U.S. Pat. No. 4,247,175 Patent Literature 5: U.S. Pat. No. 4,273,422 Patent Literature 6: U.S. Pat. No. 4,407,565 Patent Literature 7: U.S. Pat. No. 4,422,963 Patent Literature 8: U.S. Pat. No. 3,912,365 Patent Literature 9: U.S. Pat. No. 4,078,856 Patent Literature 10: Japanese Patent Application Laid-Open (JP-A) No. 2002-189123

SUMMARY

OF THE INVENTION Technical Problem

The present invention relates to a light control film used in the windowpanes or the like for use in vehicles such as automobiles, or in construction.

The transparent conductive layer of light control films used in the windowpanes for use in vehicles such as automobiles, trains and airplanes or use in construction, is a transparent conductive layer having low electrical resistance. Since low electrical resistance is simultaneously accompanied by high radio wave reflectivity, there is a problem that television sets, mobile telephones, remote control devices utilizing radio waves, and the like do not function adequately when these have been brought into a car or into a room.

Furthermore, there is also a problem with the adhesiveness between the transparent resin substrate and the transparent conductive layer of the transparent conductive resin substrate.

Solution to Problem

The inventors of the present invention conducted a thorough investigation, and as a result, they found that the problems described above could be solved by adopting a configuration in which a conductive polymer is incorporated in an organic binder, for the transparent conductive layer of the transparent conductive resin substrate.

Specifically, the present invention provides the following.

(1) A light control film comprising: two of transparent conductive resin substrates each having a transparent conductive layer and a transparent resin substrate; and a light control layer interposed between the two transparent conductive resin substrates to be in contact with the transparent conductive layer sides, the light control layer containing: a resin matrix; and alight control suspension dispersed in the resin matrix,

wherein the transparent conductive layer contains: an organic binder resin; and a conductive polymer.

(2) The light control film as described in the above item (1), wherein the conductive polymer is at least one selected from the group consisting of a polythiophene derivative, a polyaniline derivative, and a polypyrrole derivative.

(3) The light control film as described in the above item (1) or (2), wherein the conductive polymer is a resin obtainable by curing a polymerizable monomer or a polymerizable oligomer with heat or light.

(4) The light control film as described in any one of the above items (1) to (3), wherein the entirety or a portion of the organic binder resin is composed of (meth)acrylate containing a hydroxyl group.

(5) The light control film as described in any one of the above items (1) to (4), wherein the entirety or a portion of the organic binder resin is composed of urethane acrylate containing a pentaerythritol skeleton.

(6) The light control film as described in any one of the above items (1) to (5), wherein the transparent conductive layer has a surface resistivity value of 1000Ω/□ or greater.

(7) The light control film as described in any one of the above items (1) to (6), wherein the radio wave shielding property in the frequency region of 500 MHz or higher is 5 dB or less.

Advantageous Effects of Invention

The light control film of the present invention has excellent radio wave transparency, so that even inside a space surrounded by the light control film, television sets, mobile telephones, remote control devices utilizing radio waves, and the like can be made to function adequately. Furthermore, when a particular organic binder resin is used, the adhesiveness between the transparent resin substrate and the transparent conductive layer of the transparent conductive resin substrate can be made satisfactory.

The disclosure of the present application relates to the subject matters described Japanese Patent Application No. 2010-14191 filed on Jan. 26, 2010, the disclosure of which is incorporated herein by reference.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view of the cross-sectional structure of an embodiment of the light control film of the present invention.

FIG. 2 are each a schematic view for explaining the operation in the case when an electric field is not applied to the light control film in FIG. 1.

FIG. 3 are each a schematic view for explaining the operation in the case when an electric field is applied to the light control film in FIG. 1.

FIG. 4 is a schematic view for explaining the state of an edge of the light control film. Illustration of light control particles 10 in liquid droplets 3 is omitted.

FIG. 5 is a diagram showing the results for the measurement of the radio wave shielding effect in the frequency region of 1 kHz to 1 GHz (Examples 1 to 3 and Comparative Examples 1 and 2).

FIG. 6 is a diagram showing the results for the measurement of the radio wave shielding effect in the frequency region of 1 GHz to 18 GHz (Examples 1 to 3 and Comparative Example 1).

BEST MODES FOR CARRYING OUT THE INVENTION

The light control film of the present invention is a light control film wherein a light control layer containing: a resin matrix; and a light control suspension dispersed in the resin matrix, is interposed between two transparent conductive resin substrates to be in contact with a transparent conductive layer sides, and is characterized in that the transparent conductive layer contains: an organic binder resin; and a conductive polymer.

The light control film can be generally formed by using a light control material. The light control material according to the present invention contains: as a resin matrix, a polymeric medium which is cured when irradiated with an energy beam; and a light control suspension in which light control particles are dispersed in a dispersion medium in a flowable state. It is preferable that the dispersion medium in the light control suspension be capable of phase separation from the polymeric medium and a cured product thereof.

When the light control material is used, and a light control layer in which a light control suspension is dispersed in a resin matrix formed from a polymeric medium, is interposed between two transparent conductive resin substrates each having a transparent conductive layer containing: an organic binder resin; and a conductive polymer, to be in contact with the transparent conductive layer sides, the light control film of the present invention is obtainable.

That is, in the light control layer of the light control film of the present invention, the liquid light control suspension is dispersed in the form of fine liquid droplets inside a solid resin matrix which is a cured product of the polymeric medium. The light control particles that are contained in the light control suspension are preferably rod-shaped or needle-shaped.

When an electric field is applied to such a light control film, the light control particles having an electric dipole moment, which are suspended and dispersed in the liquid droplets of the light control suspension dispersed in the resin matrix, are arranged in parallel to the electric field. Thereby, the liquid droplets are converted to a transparent state with respect to the incident light rays, and thus the light control film transmits the incident light rays in astute in which scattering due to the viewing angle or a decrease in transparency is almost absent.

According to the present invention, when a configuration of incorporating an organic binder resin and a conductive polymer is adopted for the transparent conductive layer, the conventional problems of light control films (that is, the problems that inside a space surrounded by the light control film, television sets, mobile telephones, remote control devices utilizing radio waves, or the like do not function adequately, and the use of ETC is restricted, since the radio wave transparency is small) are solved.

According to the present invention, the surface resistivity of the transparent conductive layer is preferably 1000Ω/□ or greater, and more preferably 2000Ω/□ or greater. Furthermore, the radio wave shielding property of this light control film in the frequency region of 500 MHz or higher is preferably 5 dB or less, and more preferably 3 dB or less.

As long as the transparent conductive layer is such that if the surface resistivity is 1000Ω/□ or greater, there are no particular limitations on the material to be used. However, for example, it is preferable to use at least one selected from the group consisting of a polythiophene derivative, a polyaniline derivative, and a polypyrrole derivative, as the conductive polymer.

Furthermore, it is preferable to use a resin that is obtainable by curing a polymerizable monomer or a polymerizable oligomer with heat or light, as the organic binder resin. It is more preferable that the entirety or a portion of this organic binder resin be composed of (meth)acrylate containing a hydroxyl group or urethane acrylate containing a pentaerythritol skeleton.

The details of the adjustment of the surface resistivity will be described below,

Hereinafter, each layer configuration and the light control film will be described.

<Transparent Conductive Resin Substrate>

As the transparent conductive resin substrate used in the case of producing a light control film using the light control material according to the present invention, use can be made of a transparent conductive resin substrate which has a transparent resin substrate coated with a transparent conductive layer containing an organic binder resin and a conductive polymer, and having a combined light of the transparent resin substrate and the transparent conductive layer is 80% or greater. Meanwhile, the light transmittance can be measured according to the method for measuring the total light transmittance of JIS K7105.

(Transparent Conductive Layer)

First, the material used in the transparent conductive layer according to the present invention will be described.

The transparent conductive layer is such that there are no particular limitations on the material to be used, as long as the material contains an organic binder resin and a conductive polymer. However, examples of the material of the conductive polymer used in the transparent conductive layer include a polythiophene derivative, a polyaniline derivative, and a polypyrrole derivative, and at least one of these is used as the conductive polymer.

Specific examples of the material used as the conductive polymer include compounds represented by the following (formula a) to (formula d) (a polythiophene derivative, a polyaniline derivative 1, a polyaniline derivative 2, and a polypyrrole derivative), but the present invention is not intended to be limited to these examples.

Polythiophene Derivative

As the polythiophene derivative represented by the formula a, such a polymer having a structural unit represented by polystyrenesulfonic acid (the upper part of formula a) and having a weight average molecular weight in the range of 30,000 to 75,000 is preferred, and the poly-3,4-ethylenedioxythiophene (the lower part of formula a) is preferably such a polymer having 5- to 15-mers of the thiophene unit.

Examples of polythiophene derivatives that are represented by the (formula a) and are available include Clevios PH 1000: product name, manufactured by H.C. Starck GmbH (having a structural unit represented by polystyrenesulfonic acid (the upper part of formula a), weight average molecular weight: 40,000, thiophene unit: 5- to 10-mers), and Clesious S V3: product name, manufactured by H.C. Starck GmbH (having a structural unit represented by polystyrenesulfonic acid (the upper part of formula a), weight average molecular weight: 40,000, thiophene unit: 5- to 10-mers).

Polyaniline Derivative 1

A preferred example of the polyaniline derivative 1 represented by the above formula b may be such a polymer having a weight average molecular weight in the range of 15,000 to 100,000, with X being a dopant of a sulfonic acid compound.

Examples of the polyaniline derivatives 1 that are represented by the above formula b and are available, include NX-D103X: product name (X=sulfonic acid compound) and NW-F102ET: product name (X=sulfonic acid compound) manufactured by Ormecon GmbH.

Polyaniline Derivative 2

A preferred example of the polyaniline derivative 2 represented by the above formula c may be such a polymer having a weight average molecular weight in the range of 2,000 to 100,000, in which R is —OCH3.

Examples of the polyaniline derivatives 2 that are represented by the above formula c and are available include aquaPASS (registered trademark)-01x: product name, manufactured by Mitsubishi Rayon Co., Ltd. (weight average molecular weight: 10,000, x=1 and y=1).

Polypyrrole Derivative



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stats Patent Info
Application #
US 20120314276 A1
Publish Date
12/13/2012
Document #
13575108
File Date
01/26/2011
USPTO Class
359296
Other USPTO Classes
International Class
02F1/167
Drawings
4


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